Oxidation inhibitor



latented June 2 3, 19552 UNITED STAT OXIDATION INHIBITOR Harry W. Rudel, Roselle Park, and James M. Boyle, Bayonne, N. J., assignors to Standard Oil Development Company,'a corporation of Delaware No Drawing.

Application September 1+. 1949, Serial No. 116,404

8 Claims. (Cl. 260- 432) The present invention relates to mineral, oil compositions containing as an additive an oxidation inhibiting or corrosion resisting agent.

Oxidation inhibiting addition agents for mineral oils, and especially for mineral lubricating oils, have been previously made by sulfurizing fats, fatty oils and hydrocarbon materials with free sulfur by heating at an elevated temperature, and while such products have been used for many years, they are not entirely satisfactory because the sulfurization is commonly accompanied by side reactions such as cracking, polymerization, and the like, which give rise to inactive constituents and darkly colored bodies, some of which, may be merely useless while others are decidedly objectionable.

It is known that sulfurized materials of a more satisfactory character can be formed by sulfurizing olefin hydrocarbons, especially the polymers of low molecular weight olefins, and more specifically the polymers of propylene, the butylenes, and the amylenes. These materials may be sulfurized by heating with free sulfur, but ithas been found that a more satisfactory product from the standpoint of color, oil solubility, lack of copper-staining tendency and odor can be obtained by sulfurizing with a sulfur halide, such as sulfur monochloride or sulfur dichloride. Unfortunately, it is diflicult to free the product from a considerable proportion of the halogen. An amount of halogen up to 10% or greater will remain in the sulfurized product even after heating for long periods of time. For certain purposes such amounts of halogen are very objectionable, especially where corrosion is to be avoided.

In accordance with the present invention an Y aliphatic, cycloaliphatic, or other non-aromatic hydrocarbon which has been sulfurized by means of a sulfur halide can be dehalogenated with little difficulty and at the same time converted into a product containing additional $111- fur by heating such sulfurized and halogenated aromatic hydrocarbons containing a "double:

bond carbon-to-carbon linkage. This group of materials includes the olefins, e'. g., p'ropylenes, triisobutylnes, the

butylenes, diisobutylenes, codimer' of isobutylene and n-butylen'e; also cracked gasoline fractions, cracked paraffin wax, viscous olefin polymers such as medium or high molecular weight polybutenes, cyclopentene, cyclohexene, butadiene, pentadiene, 'isoprene, dipentene, 'a-pinene, ,B-p'inene, terpinolene, camphene, fenchene, A 2,4(8)-p-menthadiene, and the like.

I paring sulfurizedj mineral oil additives, buton the other hand the hydrocarbon may contain as many as thirty carbon atomsper molecule. Derivatives of the above describedcompounds containing various non-reactive substituent groups and atoms, e. g., nitro groups, may be used to advantage, since such groups or atoms would not interfere with the sulfurization reaction or the dehalogenating process herein de-'.

scribed.

The alkali metal dithiocarbamates, of which the sodium dithiocarbamates are a preferredv group, include generally any alkali metal dithiocarbamate, but the preferred compounds are those of the formula s R MS N where M is an alkali metal and R, is hydrogen or a hydrocarbon radical containing 1 to 18 carbon atoms. Preferred examples of alkali metal dithiocarbamates include sodium dithiocarbamate, sodium methyl dithiocarbamate, sodium ethyl, dithiocarbamate, sodium butyl dithiocare 7 suitable inert medium such as methylethyl ketone. The solution of the dithiocarbamate thus formed may be used directly in the reaction with the sulfurized and halogenated hydrocarbon, in accordance with the present invention.

For the preparation of the sulfurizedhydrocarbons the most suitable sulfur halides are sul fur dichloride and monochloride, especially the latter. The olefinic material and sulfur halides are generally reacted in molal ratios from about Hydrocarbons of less than three. carbon atoms are not generally employed in pre- 3:1 to about 1:1. Higher ratios of olefinio materials are sometimes used when a portion of the same is to serve as a solvent to be removed later as unreacted material. The temperatures which have been found most satisfactory for this reaction are from about 50 to 100 C., butthe method may be carried out at higher or lower temperatures if desired. Catalysts are not required.

In the dehalogenating process of the present invention the sulfurized and halogenated prod not is merely heated in the presence of the alkali metal dithiocarbamate, preferably at. temperatures from about 50 to 150 C1 The reaction may be caused to take place either with or without the presence of a solvent, but it is generally preferred to employ a solvent, such as ethyl alcohol, isopropyl alcohol, acetone, methylethyl ketone, diethylene oxide, and the like. The heating is conveniently carried out under refluxing conditions. The dehalogenation is generally accomplished within aperiod of two hours or less. It is preferable to employ an amount of alkali metal dithiocarbamate which is a stoichiometrical equivalent of the halogen which is present in the sulfurized and halogenated; hydrocarbon product. If a solvent is employed, one should be selected in which the alkali metal halide by-product is insoluble, in order that the by product will be precipitated out of solution and be readily removed by decantation or filtration. If desired, additional sulfur 'may may be present during the dehalogenation reaction, and an additional amount of sulfur may thus be introduced into the final product.

.When the products of the present invention are-added to mineral oils for the purpose of inhibiting oxidation of the same when in contact with air, they are preferably added in proportions of 0.001 to about 5%,- preferably 0.01 to"2%. The proportions giving-the best results in given cases will vary' somewhat according to the nature of the additive and of the base oil and in accordance with the specific purpose the oil is to serve in a; given. case. For commercial purposes,- when the additive is to be employed in mineral lubricatin oils, it is convenient to prepare concentrated lubricating oil solutions in which the amount of the additive in the composition ranges from to by weight, and to transport and store them in such form. In preparing a lubricating oil composition for use, as in the crankcase of and internal combustion engin'e', the additive concentrate is merely blended with the base oil in therequired amount.

Below are given detailed descriptions of 'the preparation and testing 'of an example of a mineral oil additive prepared in accordance with the method of the present invention. It is to beunderstood that this example is given by way of-illustration only andis not to be construed as limiting the scope of the present invention in any way.

Eztdmple 1' rt-in mixture was maintained betweenq'sot Analysis: 7 A

Chlorine:- 14 .16 Sulfur =28.26%

(b) 40 grams of finely ground sodium hydroxide was suspended in 500 cc. of methylethyl ketone and 73- grams of n-butylamine added. The mixture was-cooled in an ice bath and 83.7 grams of carbon disulfide (diluted with cc. methylethyl ketone') added dropwise while stirring the reaction mixture. After the addition was'complete, the orange colored sodium butyl dithiocarbamate solution was stirred at room temperature for an additional two hours.

(e) The reaction product of (a) (220 grams) was added to the sodium butyl dithiocarbamate solution of (b)- and the mixture heated'atrefluxingtemperature for two hours with'agitation. Thereaction mixture was filtered toremove the precipitated sodium chloride and. the solvent stripped by distillation and nitrogen blowing at about 0.

Analysis:

Chlorine' 'l racia i Sulfur=-30.97%

Nitrogen-3.15

' Example '2.L'a"uso7z engine .i'est The sulfurized "diisobutylene-dithiocarbamate product'prepared as desc'ribedin Example'l was tested in a Lausoni enginausing ablend of 10% by weight of the additive in a solvent extracted naphthenic oil of SAE 30 grade. Fo'r compari son, a sample of the un'blended base oilwas -likewise tested. The test was conducted for a' period of 25.hours, the Lauson engine being operated-at 1800' R. P; M; with a 1.5. indicated kilowatt load; 300. F. oil. temperature sand 295 water jacket temperature: The oils iwerera'ted on a'demerit system wherein raLperfectIy cIean surface is given a rating of 0, whilea rating of 10 is'giv'en to the worst condition which. can be expected on that surface; Observations werealso made on the loss inLWeight' or: the copper-lead bearing during the test; The.resultsrareishown inithe following table:

r i s i l -ti B -ii Lubricant Varnish .W eight Loss Demezit (GM.-/Bearing) Unblended base oil I is o 137 Base oil 1% product of Exam le I 01 008 Example 3.'Ilaboraiory bearing-corrosion test A blend was prepared containing"0.2 5'% by Weight ofthe additive prparedas described ill Example L using as the base onaiseive t-ext acteq Mid=Continent parafiinic' ubricating on 'jof- SAE- so grade. A ample-or this-man ate a sample of the unblended base enteresubmitted to a laboratory test designed to measure-the efe fectiveness of the additive in inhibiting the corrosiveness of a typical mineral lubricating oil towards the surfaces of copper-leadr'bearmg's. The-test-was conducted as follows:

500 cc. of the'oil-wasplaced-ina glass oxide tion-tube (l 3- inches long and2 /g ihchesifi di ameter) fitted at the bottom-with a; 'ihch'air inlet tube perforated to facilitateairdistributicn.

ing bath so that theoil temperature was maintained at 325 F. during the test. Two quarter sections of automotive bearings of copper-lead alloy of known weight having a total area .of 25 sq. cm. were attached to opposite sidesiof a stainless steel rod which was then immersed in'the test oil and rotated at 600 R. P. M., thus pro-viding sufiicient agitation of the sample during the test. Air was then blown through the oil at the rateof -2 cu. ft. per hour. At the end of. each four-hour period the bearings were removed, washed with naphtha and weighed to determine the amount or loss by corrosion. The bearings were then repolished (to increase the severity oi the test), reweighed, andthen subjected to the test for additional four-hour periods in like manner. The results are given in the following table as corrosion life," which indicates the number of hours required for the bearings to lose 100 mg. in weight, determined by interpolation of the data obtained in the various periods.

It can be seen from the results shown above that the products prepared in accordance with the presentinvention are particularly effective in reducing the corrosion of copper-lead bearings and do not substantially increase the formation of varnish on engine parts.

The products of the present invention may be employed not only in ordinary hydrocarbon lubricating oils but also in the heavy duty type of lubricating oils which have been compounded with such detergent type additives as metal soaps, metal petroleum sulfonates, metal phenates, metal alcoholates, metal alkyl phenol sulfides, metal organo phosphates, thiophosphates, phosphites and thiophosphites, metal salicylates, metal xanthates and thioxanthates, metal thiocarbamates, amines and amine derivatives, reaction products of metal phenates and sulfur, reaction products of hydrocarbons such as polyisobutylene or bright stock with phosphorus sulfides, reaction products of metal phenates and phosphorus sulfides, metal phenol sulfonates and the like. Thus the additives of the present invention may be used in lubricating oils containing such other addition agents as barium tert.-actylpheno1 sulfide, calcium tert.-amylphenol sulfide, cadmium oleate, nickel oleate, barium octadecylate, calcium phenyl stearate, zinc diisopropyl salicylate, aluminum naphthenate, calcium cetyl phosphate, barium di-tert.-amylphen0l sulfide, calcium petroleum sulfonate, zinc methylcyclohexyl thiophosphate, calcium dichlorostearate, etc. Other type of additives, such as phenols and phenol sulfides, may be employed.

The lubricating oil base stocks used in the compositions of this invention may be straight mineral lubricating oils or distillates derived from paraffinic, naphthenic, asphaltic, or mixed base crudes, or, if desired, various blended oils may be employed as well as residuals, particularly those from which asphaltio constituents have been carefully removed. The oils may be refined by conventional methods using acid, alkali and/or clay or other agents such as aluminum chloride, or they may be extracted oils produced, for example, by solvent extraction with solvents such as. .phenol, sulfur dioxide, furfural, dichloro diethyl ether, nitrobenzene, crotonaldehyde, etc.

Hydrogenated oils or white oils may be employed as well as synthetic oils prepared, for example,

by the polymerization of olefins or by the reaction of oxides of carbon with hydrogen or by the hydrogenation of coal, or its products. In

certain instances cracking coil tar fractions and coal tar or shale oil distillates may also be used. Also, for special applications, animal,-vegetable or fish oils or their hydrogenated or voltolized in the service contemplated. However, since one advantage of the additives is that their usefalso makes feasible the employment of less satisfac tory mineral oils or other oils, no strict rulecan be laid down for the choice of thebasestock." Certain essentials must of course be-observed.v

The oil must possess the viscosity and volatility characteristics known to be required for'the serv ice contemplated. The oil must be a satisfactory solvent for the additive, although in some cases 7 auxiliary solvent agents may be used. The lubrieating oils, however they may have been'produced, may vary considerably in viscosity and other properties depending upon the particular use for which they are desired, but they usually range from about 40 to 150 seconds (Saybolt'i Y viscosity at 210 F. For the lubrication of certain low and medium speed diesel engines, the general practice has often been to use a lubricating oil base stock prepared from naphthenic or aromatic crudes and having a Saybolt viscosity at 210 F. of 45 to seconds and a viscosity index of 0 to 50. However, in certain types of diesel engine and gasoline engine service, oils of higher viscosity index are often preferred, for example, up to '75 to 100, or even higher, viscosity index.

In addition to the material to be added according to the present invention, other agents may also be used such as dyes, pour point depressants, heat thickened fatty oils, sulfurized fatty oils, organo-metallic compounds, metallic or other soaps, sludge dispersers, antioxidants, thickeners, viscosity index improvers, oiliness agents, resins, rubber, olefin polymers, voltolized fats, voltolized mineral oils, and/or voltolized waxes and colloidal solids such as graphite or zince oxide, etc. Solvents and assisting agents, such as esters, ketones, alcohols, aldehydes, halogenated or nitrated compounds, and the like may also be employed.

Assisting agents which are particularly desirable as plasticizers and defoamers are the higher alcohols having eight or more carbon atoms and preferably eight to twelve carbon atoms, e. g., lauryl alcohol, stearyl alcohol, wax oxidation alcohols, and the like.

In addition to being employed in lubricants, the additives of the present invention may also be used in other mineral oil products, such as motor fuels, hydraulic fuels, torque converter fluid, cutting oils, flushing oils, turbine oils, transformer oils, industrial oils, process oils, and the like, and generally as antioxidants in mineral oil products. They may also be used in gear lubricants, greases and other products containing mineral oils as ingredients.

What is claimed is:

l. The method which comprises reacting a double-bonded non-aromatic hydrocarbon with a sulfur halide to form a hydrocarbon product with added sulfur-1 and: halogen; and fur-then re- 7 actingsuch product with an alkali metahdiizl'ii'o-v carbamate, the amount of said alkali metal. di-r thiocarba mate being stoichiomet-rically' equiv'a lent; to the halogenated product, at a temperature in the range of. about;- 50 16150 C; whereby s'aid halogen is substantially completely rep-laced by" dithib'earbamate radical and bymmmet alkali mtaIhalide is formed. 7

2L Ainethodaccordingto elaim-l vcgmenthe reaction wan the alkali metal dithioca'rbainate is conducted in a medium in-Whi'eh tlie=by-prod uct metal halide is insoluble.

3 Amthod according to-claim 2m Which-the dou ble bond'ednon a-rom'atic hydrocarbon is anolefin smel in which the'sulfilr' hal-i'de is a sulfur chloride;

4: 15: memoir according to claim- 3- in which we Olefin is dii's obutylen'e ai'icl' in Whichthe su'lfur chloride is 'sulfur' mo'nochljoride;

5. A method according lio Claim 4 in Whieh'the alkali metal-I dithiooarbamate' is sodium butylditnioc'arbamate.

6; methodacoording to claim- Sin-"which the sodium" butyl dithiooarbamaiie is readied Withfihe sulf nrized andhalogenated di'isobutylene the presence otmethylethyl-ketone as a solventaii the refliixing temperature of the solution.

"T. The product obtained by reacting a doublebonded non aromati'c hydrocarbon wan a sulfur lnal'itit toform ahydrocarbon product-containmeadded sulfur andhalo'gen; and f-ii'rther' reacting suelrprodiict witharr alkali met-a1 dithibearbam ate, .the amount. .of said :dithiocarbamate; being" stoichiometrically equivalent "to .the' I halogenin the halogenated. product, at a temperatur e'.in.the range of about to,150,.C.wherebysaid'halogen is substantially completely replaced "by dithio carbamatelradical. ,2 .2 v

8; The; product obtai'ried'by reacting .d-iis'objutyle ene with;- a; substantially; equivalent" molecular proportion oflsulfurl rrionochloride.- and: further reacting .the, product'uthus' ,formed' with sodium:

butyl. ditliiocarbamate in an, amount which is} stoich'iometrically equivalent to the-chlorine; present in the said first reaction x'J'roduct at a" .temperature of 50? to C3, andremoving'rhebyk product-sodium chloride from. the. v organie re action product, said reaction product'being sub stantiallyfree of chlorine.

w; RUIQEL. JAMES Ml BOYLE.

REFERENCES CITED The following, references are of record in the file of this patent:

UNITED STATES PATENTS 

1. THE METHOD WHICH COMPRISES REACTING A DOUBLE-BONDED NON-AROMATIC HYDROCARBON WITH A SULFUR HALIDE TO FORM A HYDROCARBON PRODUCT WITH ADDED SULFUR AND HALOGEN, AND FURTHER REACTING SUCH PRODUCT WITH AN ALKALI METAL DITHIOCARBAMATE, THE AMOUNT OF SAID ALKALI METAL DITHIOCARBAMATE BEING STOICHIOMETRICALLY EQUIVALENT TO THE HALOGENATED PRODUCT AT A TEMPERATURE IN THE RANGE OF ABOUT 50* TO 150*C. WHEREBY SAID HALOGEN IS SUBSTANTIALLY COMPLETELY REPLACED BY DITHIOCARBAMATE RADICAL AND BY-PRODUCT ALKALI METAL HALIDE IS FORMED. 